The irradiation power of a laser diode can change for a variety of reasons, such as deterioration of the laser diode over time and/or changes in the internal temperature of the laser diode due to use and/or changes in the temperature of the operating environment of the circuit in which the laser diode is included. Therefore, the irradiation power of a laser beam emitted from a write/read laser optics module of an optical disc drive during an optical media write process is closely monitored, and adjusted when necessary, to maintain the laser irradiation power at intended levels. Generally, laser diode irradiation power is monitored using a light sensitive diode, such as a front monitor diode, or forward sensor.
A laser diode can be monitored by sampling an analog signal produced by the light sensitive diode in response to a portion of the light emitted from the laser diode. However, such an analog monitoring signal will include delays and distortions that make it difficult to determine proper times at which to sample the analog monitoring signal in order to obtain accurate feedback for a specific write power level. The task is further complicated by the fact that some of the delays and distortions that affect the analog monitoring signal are synchronous in nature, i.e., change based on the clock speed at which data is written by the diode laser, while other delays and distortions are asynchronous in nature, i.e., change based on one or more analog physical response characteristics of the electronic components in response to changes in the write speed and write power of the laser diode.
The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.